This invention relates to a process for removing capsule oils from carbonless copy paper in the presence of nonionic surfactants as additive. The invention also relates to the use of these nonionic surfactants for removing capsule oils from carbonless copy paper.
Wastepaper is now being increasingly used for the manufacture of, for example, newsprint and sanitary paper. A special type of wastepaper is so-called carbonless copy paper. Carbonless copy papers contain microcapsules in which dye precursors and so-called capsule oils are present. The function of these capsule oils is to dissolve and/or disperse the dye precursors present in the microcapsules. Now, in the remanufacture of carbonless copy paper, the microcapsules are destroyed by the mechanical stressing the paper undergoes during the slushing step so that the capsule oil is released.
The remanufacture of carbonless copy paper is normally carried out in two steps. The first step is compulsory, the second optional.
The first step in the remanufacture of carbonless copy paper, so called disintegration, may be described as follows: disintegration is generally understood by the expert to be the process of defibration of wastepaper--in the present case the defibration of carbonless copy paper. This process may be induced, for example, in aqueous medium by the application of mechanical energy, for example by stirring. In the case of carbonless copy paper, defibration is accompanied by substantial destruction of the microcapsules present in the paper, the capsule oils they contain being released.
In the second step of the remanufacturing process, the stock suspension is washed and/or subjected to flotation.
If the remanufacturing process mentioned is carried out in the absence of special additives, studies conducted by applicants have shown that around 86% of the capsule oils are removed without washing and/or flotation and that around 94% are removed where washing and/or flotation is/are carried out.
Like other office and administration papers, carbonless copy papers are increasingly entering the recycling circuit. For hygienic and functional reasons, it is desirable in this regard to remove as much of the capsule oil present in the microcapsule coating of the carbonless copy papers as possible during the recycling of fibers from these wastepapers. This prevents, for example, unwanted discoloration of the recycled fibers and the transfer of capsule oils from papers produced using these fibers to foods packed therein. This is very important in particular when the oils used in the carbonless copy papers are aromatic and/or paraffinic, for example alkylated napthalenes, alkylated biphenyls or hydrogenated oils based on mineral oils.